This application claims priority to GB Application No. 1104803.0, filed Mar. 22, 2011, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to the field of data processing and in particular to providing storage for data during secure data processing.
2. Description of the Prior Art
Keeping data secure and confidential during processing, such that the data and the processing of that data is not visible to the outside is a known problem in systems processing sensitive data. For example smart cards may store cryptographic keys that are used to encrypt confidential data that must not be accessible to a user. It has been found that the use of techniques such as differential power analysis or DPA of a system during its operation can provide data that may allow a person to determine information about the secure data such as the cryptographic keys stored within the system.
Various techniques have been devised to try to inhibit such attacks on the security of the system. For example, “Random Register Renaming to foil DPA” by May et al. describes how the use of randomly selected registers from a selection of available registers during register renaming can render the use of DPA to determine data stored less effective. When writing to a register for example, the amount of power used depends on the number of bits that are flipped, thus an analysis of the power signature and a knowledge of what was originally stored in the register may enable a user to determine information on the final value stored. If the register storing the value to be overwritten is randomly selected from a plurality of available registers, the value that is overwritten is not predetermined and without knowledge of this value DPA is less effective.
It would be desirable to provide increased security within a system processing confidential data.